RE: [CAD_CAM_EDM_DRO] Home shop power for a big machine

I have a cnc lathe with a 15hp spindle in our shop. The shop has a 200amp panel and I'm running a home made 30hp phase converter for our 3ph needs. We've never had a problem. Even with the compressor running, lights, computer, radio, and maybe a welder or plasma cutter. Seems to work fine here. I've never put pencil to paper to see what max draw is on all these items during startup to (maybe I should), but I never had any problems or noticed the lights diming. Maybe we've just been lucky??
Shawn




To: CAD_CAM_EDM_DRO@yahoogroups.comFrom: elson@...: Wed, 31 Dec 2008 13:03:29 -0600Subject: Re: [CAD_CAM_EDM_DRO] Home shop power for a big machine



vrsculptor wrote:> I was lusting over a big VMC that would never fit in my home shop and> got to wondering about power. The machine's data plate says 230 volts> 3PH @ 80 AMP's, 18KVA. It has a 15 HP spindle. >> I could use a rotary phase converter to generate the three phase but> don't have anywhere near 80 AMP's available. 18KVA/750 watts equals a> 24 HP phase converter.>> If you where using this machine in a hobby environment and not trying> to get production feeds and loads how small of a phase converter could> you get by with?> I think even with 200 A service in a typical home, you are really pushing it! The line current into a typical rotaty phase converter is going to be REALLY high with a machine like this. If you trip the breaker out on the transformer, the power company is going to get QUITE nosy about what you are doing. If you have your own dedicated pole transformer, you might get away with it. Especially if the local setup has a 50 KVA transformer on the pole. If you have a 25 KVA transformer shared between 4 residences, you will NEVER get away with it, and you'll have a bunch of angry neighbors, too.It is possible that the machine really doesn't need 3-phase at all. If the servo drives are PWM (not phase-controlled SCR) they may run fine on single-phaee power. If a VFD is used for spindle speed control, it may be able to run off single phase at reduced output.Jon






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